There was an intention to use the Cuk configuration circuit again, like the old circuit in EDN, but with an output voltage of about -1 V only and a low—less than 2 mA—output current. While exploring ...

A TCS3200 color sensor is a much better choice, and you can buy a nice assemble module for about $2 from our friends in Shenzhen. And before you say the point here is DIY, DIY doesn’t mean 20 ...